I've previously successfully set up Exchange 2010 with a wildcard certificate, but I remember it wasn't exactly straightforward. I'm also more familiar with generating CSRs with openssl than Windows tools. My question is in two parts:

  1. would life be simpler if I did not use a wildcard cert?
  2. can I use a certificate in Exchange if I've had it issued against a CSR generated with openssl?

1 Answer 1


We use a web-based front-end to OpenSSL to generate the CSR and private key, and the same tool to build the PFX from the key and issued certificate. Works great.

NOTE: A configuration change is required for legacy clients if you use a wildcard certificate: http://technet.microsoft.com/en-us/library/cc535023(v=exchg.80).aspx

You can either generate a wildcard certificate for your email domain, or a unified communications/SAN certificate. If you aren't sure which subject alternative names to include in the UC certificate, you may want to use the wizard in the EMC to generate your CSR. Be sure to include any publicly accessible client-access hostnames and autodiscover.domain.com. Also include your send connector FQDNs if you want to utilize TLS for transport.

  • does this achieve the same thing as your tool?
    – user83664
    Apr 10, 2013 at 17:11
  • hard to see links in comments here isn't it?
    – user83664
    Apr 10, 2013 at 17:12
  • 1
    It is hard to see links in comments, which is why I've resorted to pasting URLs instead of hyperlinking. It looks like they do use the same parameters: /usr/bin/openssl pkcs12 -export -in /path/to/server.crt -inkey /path/to/server.key -certfile /path/to/cabundle.crt -out /path/to/new/server.pfx -passout file:/path/to/password.txt Apr 10, 2013 at 17:48

You must log in to answer this question.